Carbidopa and Levodopa (Page 4 of 4)
OVERDOSAGE
Management of acute overdosage with carbidopa and levodopa is the same as management of acute overdosage with levodopa. Pyridoxine is not effective in reversing the actions of this product.
General supportive measures should be employed, along with immediate gastric lavage. Intravenous fluids should be administered judiciously and an adequate airway maintained. Electrocardiographic monitoring should be instituted and the patient carefully observed for the development of arrhythmias; if required, appropriate antiarrhythmic therapy should be given. The possibility that the patient may have taken other drugs as well as carbidopa and levodopa tablets should be taken into consideration. To date, no experience has been reported with dialysis; hence, its value in overdosage is not known.
Based on studies in which high doses of levodopa and/or carbidopa were administered, a significant proportion of rats and mice given single oral doses of levodopa of approximately 1500 to 2000 mg/kg are expected to die. A significant proportion of infant rats of both sexes are expected to die at a dose of 800 mg/kg. A significant proportion of rats are expected to die after treatment with similar doses of carbidopa. The addition of carbidopa in a 1:10 ratio with levodopa increases the dose at which a significant proportion of mice are expected to die to 3360 mg/kg.
DOSAGE AND ADMINISTRATION
The optimum daily dosage of carbidopa and levodopa must be determined by careful titration in each patient. Carbidopa and levodopa tablets are available in a 1:4 ratio of carbidopa to levodopa (25 mg/100 mg) as well as 1:10 ratio (25 mg/250 mg and 10 mg/100 mg). Tablets of the two ratios may be given separately or combined as needed to provide the optimum dosage.
Studies show that peripheral dopa decarboxylase is saturated by carbidopa at approximately 70 to 100 mg a day. Patients receiving less than this amount of carbidopa are more likely to experience nausea and vomiting.
Usual Initial Dosage: Dosage is best initiated with one tablet of carbidopa and levodopa 25 mg/100 mg three times a day. This dosage schedule provides 75 mg of carbidopa per day. Dosage may be increased by one tablet every day or every other day, as necessary, until a dosage of eight tablets of carbidopa and levodopa 25 mg/100 mg a day is reached.
If carbidopa and levodopa 10 mg/100 mg is used, dosage may be initiated with one tablet three or four times a day. However, this will not provide an adequate amount of carbidopa for many patients. Dosage may be increased by one tablet every day or every other day until a total of eight tablets (2 tablets four times a day) is reached.
How to Transfer Patients from Levodopa: Levodopa must be discontinued at least twelve hours before starting this combination product. A daily dosage of carbidopa and levodopa should be chosen that will provide approximately 25% of the previous levodopa dosage. Patients who are taking less than 1500 mg of levodopa a day should be started on one tablet of carbidopa and levodopa 25 mg/100 mg three or four times a day. The suggested starting dosage for most patients taking more than 1500 mg of levodopa is one tablet of carbidopa and levodopa 25 mg/250 mg three or four times a day.
Maintenance: Therapy should be individualized and adjusted according to the desired therapeutic response. At least 70 to 100 mg of carbidopa per day should be provided. When a greater proportion of carbidopa is required, one 25 mg/100 mg tablet may be substituted for each 10 mg/100 mg tablet. When more levodopa is required, each 25 mg/250 mg tablet should be substituted for a 25 mg/100 mg tablet or a 10 mg/100 mg tablet. If necessary, the dosage of carbidopa levodopa 25 mg/250 mg may be increased by one-half or one tablet every day or every other day to a maximum of eight tablets a day. Experience with total daily dosages of carbidopa greater than 200 mg is limited.
Because both therapeutic and adverse responses occur more rapidly with this combination product than with levodopa alone, patients should be monitored closely during the dose adjustment period. Specifically, involuntary movements will occur more rapidly with carbidopa and levodopa than with levodopa. The occurrence of involuntary movements may require dosage reduction. Blepharospasm may be a useful early sign of excess dosage in some patients.
Addition of Other Antiparkinsonian Medications: Standard drugs for Parkinson’s disease, other than levodopa without a decarboxylase inhibitor, may be used concomitantly while carbidopa and levodopa is being administered, although dosage adjustments may be required.
Interruption of Therapy: Sporadic cases of hyperpyrexia and confusion have been associated with dose reductions and withdrawal of carbidopa and levodopa. Patients should be observed carefully if abrupt reduction or discontinuation of carbidopa and levodopa is required, especially if the patient is receiving neuroleptics. (See WARNINGS.)
If general anesthesia is required, carbidopa and levodopa may be continued as long as the patient is permitted to take fluids and medication by mouth. If therapy is interrupted temporarily, the patient should be observed for symptoms resembling NMS, and the usual daily dosage may be administered as soon as the patient is able to take oral medication.
HOW SUPPLIED
Carbidopa and Levodopa Tablets, USP are supplied as follows:
| 10 mg/100 mg — | Each mottled blue, round flat bevelled tablet, plain on one side, engraved with “m” above the score and “711” below the score contains 10 mg of Carbidopa, USP and 100 mg of Levodopa, USP. |
| 25 mg/100 mg — | Each mottled yellow, round flat bevelled tablet, plain on one side, scored on the other side, engraved with “m” above the score and “721” below the score contains 25 mg of Carbidopa, USP and 100 mg of Levodopa, USP and is supplied in blistercards of 30 (NDC 0615-8251-39) and 15 (NDC 0615-8251-05). |
| 25 mg/250 mg — | Each mottled blue, round flat bevelled tablet, plain on one side, scored on the other side, engraved with “m” above the score and “731” below the score contains 25 mg of Carbidopa, USP and 250 mg of Levodopa, USP and is supplied in blistercards of 30 (NDC 0615-8275-39). |
Store at 25°C (77°F); excursions permitted to 15° to 30°C (59° to 86°F) [see USP Controlled Room Temperature].
Protect from light.
Dispense in a well-closed, light-resistant container as defined in the USP.
Manufactured by:
Mayne Pharma International
Salisbury South, SA 5106, Australia
Distributed by:
Mayne Pharma
Greenville, NC 27834
61739
Revised — August 2018
PRINCIPAL DISPLAY PANEL — 25 mg/100 mg
PRINCIPAL DISPLAY PANEL — 25 mg/250 mg
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| Labeler — NCS HealthCare of KY, Inc dba Vangard Labs (050052943) |
| Establishment | |||
| Name | Address | ID/FEI | Operations |
| NCS HealthCare of KY, Inc dba Vangard Labs | 050052943 | REPACK (0615-8251), REPACK (0615-8275) | |
Revised: 12/2020 NCS HealthCare of KY, Inc dba Vangard Labs
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